Light-mediated signal transduction in vertebrate retina involves the absorption of light by the chromophore of the visual pigment rhodopsin. Absorption of a photon leads to the isomerization of the chromophore, formation of activated rhodopsin, and subsequent phosphorylation of rhodopsin by rhodopsin kinase. Arrestin preferentially binds light- activated, phosphorylated rhodopsin rather than nonphosphorylated rhodopsin, thus quenching light-mediated signal transduction. It is hypothesis using recombinant arrestin constructs in which the two positively charged domains are either eliminated, substituted with negatively charged amino acids, or substituted with neutral amino acids. These constructs will be expressed in a heterologous system and the binding of these expressed arrestin proteins to phosphorylated rhodopsin will be compared to that of native arrestin.